All Questions
271
questions
0
votes
0
answers
32
views
Does two clocks moving toward each other at the same speed, then decelerating at the same rate coming to a stop create a paradox? [duplicate]
Note I have asked this question previously but upon reflection I realized I was not specific enough, leading to confusion in the answers. I have decided to ask the question again instead of editing my ...
- 361
0
votes
1
answer
68
views
If velocity is relative, why does time dilate for some observers and not others? [duplicate]
I'm trying to get my head around relativity and time dilation. What I can't figure out is how time can dilate for fast-moving observers if all velocity is relative. Here's a scenario:
Alice and Bob ...
- 109
5
votes
3
answers
643
views
Special relativity and accelerating twins
Imagine two twins synchronise their clocks and then twin A quickly accelerates to velocity v. After a time T twin B quickly accelerates to 2v and catches up with twin A. Which one will be younger? How ...
- 81
1
vote
0
answers
42
views
Radiation from a stationary charge relative to earth for a free falling observer
It is my understanding that if we have a charge at rest on earth, a free falling observer will see it radiating, as the charge is in an accelerated frame of reference. This observer can in principle ...
- 795
1
vote
0
answers
90
views
Special Theory of Relativity Contradiction [duplicate]
I’m struggling with an apparent contradiction of special theory of relativity (STR) that I cannot resolve.
Imagine two twins flying by each other in space along the same straight line but in the ...
- 11
-4
votes
1
answer
116
views
Absolute rest in special relativity
I am new to special relativity and with still little experience in Physics. I would like to know why a privileged frame of reference that determines absolute rest is not possible. I want you to ...
- 13
1
vote
2
answers
175
views
If you have two clocks moving toward each other and they both stop when they meet does it point to a paradox?
Say they both decelerate at the same rate also. If clock A sees clock B as slower than itself and clock B see clock A as slower than itself due to relativity isn't this a paradox because when they ...
- 361
0
votes
1
answer
105
views
Time observed in a clock when you start moving relative to it
There's an example given by Brian Green, https://www.youtube.com/watch?v=XFV2feKDK9E&t=17675s
To be precise the example start at 04:56:00. In brief it is as follows:
There are two persons Gracie ...
- 15
-1
votes
2
answers
79
views
Does the length of an object change after acceleration in Special Relativity? [duplicate]
In special relativity, an object (a box, perhaps) travelling at 0.5c relative to us, if it thinks it's 1lightsecond long in its own reference frame, will look 0.866 lightseconds long to us.
My ...
- 160
1
vote
1
answer
58
views
On the distinction between frame of reference and observer
A Stack Exchange answer illustrates reference frame and observer as follows:
A frame of reference means a co-ordinate system and an observer is someone using that co-ordinate system. For example I ...
user390010
0
votes
1
answer
115
views
Observed time period in distant clock when moving towards it
Imagine, 2 persons ('A' & 'B') are 6 light years apart in space, stationary to each other and with no gravitation acting on anybody. Suppose 'B' starts his clock which also shows years, months and ...
- 15
0
votes
4
answers
203
views
How to apply the time dilation formula?
I am learning special relativity and still not sure how to correctly apply the time dilation formula. Take for instance the following example:
A spaceship leaves earth and travels to Alpha Centauri 4....
- 3
0
votes
4
answers
41
views
Measurement of the velocity of a celestial body by means of (relativistic and classical) gravitational effects on clocks
Imagine a planet with the same properties as Earth, this time moving in an elliptical orbit around a black hole of a large number of solar masses. Also imagine that the surface of this planet is as ...
- 1
0
votes
0
answers
26
views
Question on Example 5.9 of Prof. Hartle Gravity textbook
I'm reading the Gravity Hartle book (ed.2003) and I'm having trouble with the question in the last part of Example 5.9 - Frequency Measured by an Accelerating Observer. More specifically the problem ...
- 1
1
vote
1
answer
89
views
What does hypersurface of simultaneity exactly mean?
HSS - "Hyper Surface of Simultaneity"
Listening to different sources online I understood that HSS for a observer represents the points that are at same moment of time.
Consider a 1d world. ...
